Linear polyglutaraldehyde



United States Patent 3,395,125 LINEAR POLYGLUTARALDEHYDE Wendell W.Moyer, (in, Parkersburg, W. Va., assignor to Borg-Warner Corporation,Chicago, Ill., a corporation ABSTRACT OF THE DISCLOSUREPolyglutaraldehyde provided by intra-intermolecular polymerization ofglutaraldehyde and a method of making same.

This case is a continuation of SN. 252,062, filed Jan. 17, 1963, nowabandoned.

Linear polymers of monoaldehydes such as formaldehyde, acetaldehyde,propionaldehyde, butyraldehyde, and the like have been prepared, and afew of these polymers have provided new and interesting plasticmaterials. Some of the more versatile polymers have found use as films,fibers, molded parts, etc. While it has been possible to preparepolymers from the monoaldehydes, as indicated, little work has been doneon the polymerization of dialdehydes.

The present invention is directed to the polymerization of a dialdehyde,namely, glutaraldehyde, a non-conjugated dialdehyde. The polymerizationof glutaraldehyde has resulted in high molecular weight, soluble(linear) polyacetal resins. The polyglutaraldehyde polymers of thisinvention are obtained by polymerizing glutaraldehyde in a stereoregularmanner, largely by an intra-intermolecular propogation mechanism to giveproducts of the general structure indicated in Equation 1 below.

Equation 1 wherein m is greater than n.

The polymerization of the glutaraldehyde is promoted by catalyst toeffect high molecular weight polymers. Catalysts that have been found tobe effective for the polymerization of the higher aldehydes, i.e., otherthan formaldehyde, have been found effective for glutaraldehyde.Examples of these catalysts are the organo-metallic compounds, metalhalides, mixed organo-metallic-metal halides, metal alkoxides, metalhydrides, and tertiary phosphines.

The polymerization will proceed over a wide temperature range, but ispreferably conducted within a range from 75" to C.

The polyglutaraldehyde polymers must be stabilized after polymerizationto prevent degradation for they are unstable when formed, as are themonoaldehyde polymers. Stabilization is accomplished by treating thepolymer in the form of a solution in an inert solvent such asdichloromethane, benzene, or the like with a hemiacetal capping reagentadded to stabilize the polymer. The hemiacetal reagent may be an esterend-group precursor, i.e., an esterifying reagent such as acetateanhydride, propionic anhydride, benzoic anhydride, etc. The esterend-group precursor is always used in conjunction with a catalyst acidacceptor such as pyridine. Other ester end-group precursors such asacetyl chloride, benzoyl chloride, and butyryl chloride are alsosuitable when used in conjunction with an acid acceptor. The labileend-groups may also be stabilized by etherifying, that is by adding anether "ice end-group precursor such as trimethyl or triethylorthoformateor orthoacetates with boron trifiuoride as a catalyst. The stabilizationserves to modify the labile endgroups of the polymer and provideend-groups which are sufficiently stable to prevent depolyrnerization.

The polymers are completely and reversibly soluble in common solventssuch as methylene chloride, tetrahydrofuran, pyridine, and benzene.

The process of making the polymers of this invention will now be furtherillustrated by the following examples. It should be understood that theexamples are given merely by way of explanation, not of limitation, andthat numerous changes and modifications may be made in the detailsWithout departing from the spirit and the scope of the invention ashereinafter claimed.

Example I Aluminum isopropoxide, 0.25 g., dissolved in 46 g. of toluenewas introduced into a 3-neck, 500 1111., round bottom flask fitted witha mechanical stirrer, addition funnel, and thermometer. An atmosphere ofdry nitrogen was maintained in the reaction flask which was partiallyemerged into a Dry Ice-acetone cooled bath maintained at a temperaturebetween 52 and62 C. A solution of 25 g. of freshly distilled, anhydrousglutaraldehyde in 54 g. of toluene was added during minutes to thestirred catalyst solution. After the addition was complete, the reactionmixture was stirred, at the prescribed temperature, an additional 18hours. The cold viscous toluene solution of the polyglutaraldehyde wascoagulated into hexane. The polymer, separated by filtration, wasredissolved in 50 ml. of anhydrous pyridine to which a mixture of 10 ml.of acetic anhydride and 2 ml. of acetyl chloride were slow- 1y added,followed by 0.5 g. of anhydrous sodium carbonate.

The acetylation was allowed to proceed with constant stirring for 1.5hours at room temperature. The acetyl stabilized polyglutaraldehyde wascoagulated into methanol, then redissolved in methylene chloride andagain coagulated into hexane. A yield of 3 g. (12 percent) white,powder-like product was obtained; M.P. 123 to 133 C. The stabilizedpolymer was readily soluble in methylene chloride, pyridine, andtetrahydrofuran. It was stable at the melting point. Transparent filmswere cast from the molten polymer by solution casting techniques. Theinfrared spectrum was in agreement with the pro posed structure. AnX-ray diffraction pattern of the polymer showed that it was crystalline.The inherent viscosity was 0.94, (0.3 g./ 100 ml. methylene chloride at25 0.).

Example II The equipment used was the same as in Example I. A solutionof 42 g. of anhydrous glutaraldehyde in 83 g. of anhydroustetrahydrofuran was added over 100 minutes to a solution consisting of0.57 g. of boron trifiuoride etherate and 68 g. of anhydroustetrahydrofuran. The reaction solution was stirred for 7 hours at 73 C.under an atmosphere of dry nitrogen. The cooling bath was removed, and asolution of 10 ml. of acetic anhydride and 2 ml. of acetyl chloride in50 ml. of anhydrous pyridine was added to the cold reaction solution.The reaction mixture was allowed to warm to room temperature, andstirring continued an additional 3 hours. The resulting solution wascoagulated into slightly alkaline methanol. The crude, stabilizedpolyglutaraldehyde was purified by dissolving in methylene chloride andrecoagulating into hexane. The product was dried under reduced pressureat room temperature. A yield of 27.2 g. (64.7 percent) of white,powder-like product was obtained. The polymer had an inherent viscosityof 0.175 (0.4 g./l00 ml. methylene chloride at 25 C.) and was stable Theequipment was the same as described in Example I. A solution of 30 g. ofanhydrous glutaraldehyde in 54 g. of anhydrous toluene was added over aperiod of 90 minutes at -50 to 60 C. to a solution consisting of 0.25 g.of aluminum triisopropoxide, 43 g. of anhydrous toluene, and 7 g. ofanhydrous hexane. The reaction was continued for 18 hours between 55 and-50 C. under dry nitrogen.

The cold reaction mixture was coagulated into ligroin. The filtered,dried product weighted 27 g. The inherent viscosity was determined to be0.55 (0.37 g./100 ml. of CH C1 at 25 C.).

A 13.2 g. portion of the crude polymer was acetylated by reaction with161 g. of acetic anhydride and 17 g. of anhydrous pyridine for 2 hoursat 40 C. followed by an additional hour in the presence of some Na CO atthe same temperature. The reaction product was precipitated frommethanol, filtered, redissolved in CH CI and reprecipitated fromligroin. After drying under vacuum, the yield was 11.33 g. (86 percentof the charge). Inherent viscosity 0.65 (0.3 g./ 100 m1. of CH CI at 25C.).

The infrared spectra of both the crude polymer as well as the acetylatedproduct were in agreement with the proposed structure. Transparent filmswere cast from the molten polymer by solution casting techniques.

Example IV The equipment and procedure were essentially the same asdescribed previously. A solution of 103 g. glutaraldehyde in 200 g. oftoluene was added to a solution of 1.03 g. of aluminum triisobutyl in152 g. of toluene at --54 to -60 C. during a period of six hours.

The catalyst was destroyed by the addition of a mixture of 80 ml. ofacetone and ml. of water. Thereafter, the reaction mixture was pouredinto a large excess of hexane whereupon a rubbery mass coagulated. Theproduct was filtered and dried in vacuum yielding 64.3 g. of a solidproduct ('62 percent), inherent viscosity of 0.10 (0.38 g./100 ml. ofcra cl at c.).

While the invention has been described in connection with thepreparation of polyglutaraldehyde under given reaction conditions, itwill be understood that the invention is capable of furthermodification, and it is not intended that the invention be limited toany particular embodiment herein disclosed. The invention should beconstrued by those skilled in the art having in mind all those changes,variations, modifications, and equivalents falling within the scope ofthe appended claims.

What is claimed is:

1. A linear, thermally stable, stereoregular, highly polymericpolyglutaraldehyde having a melting point between about 123 C. and 133C. consisting essentially of recurring acetal units of the formula:

m GHQ 11 wherein m is greater than n, said polyglutaraldehyde obtainedby (a) polymerizing glutaraldehyde at a temperature of from C. to 0 C.in the presence of a catalyst selected from the group consisting oforganometallic compounds, metal halides, mixed organometallic halides,metal alkoxides, metal hydrides and tertiary phosphines; and

(b) stabilizing said polyglutaraldehyde by adding a stabilizing agentselected from the group consisting of ester and ether end groupprecursors, said ester end group precursors selected from the groupconsisting of acetic anhydride, propionic anhydride, benzoic anhydride,acetyl chloride, benzoyl chloride and butyryl chloride, and said etherend group precursors selected from the group consisting of trimethylorthoformate, triemthyl orthoacetate, triethyl orthoformate, andtriethyl orthoacetate.

2. The polymeric composition of claim 1 wherein said material isobtained by intra-intermolecular polymerization of glutaraldehyde.

3. The polymeric material of claim 1 wherein the polymeric material isstabilized by adding an ester end group precursor in conjunction with anacid acceptor.

References Cited UNITED STATES PATENTS 3,087,913 4/1963 Kray et al.26073 3,288,756 11/1966 Buckley 260-67 3,184,433 5/1965 Vogl 260-673,215,675 11/1965 Koral et al. 26067 OTHER REFERENCES Aso et al.:Bulletin of Chemical Society of Japan, vol. 35 No. 8 (1962), p. 1426,QD1C65.

Meyers-en et al.: Die Makromolekulare Chemie, vol. 58, (1962), pp.204-216, QD 281P6M2.

Ove'rberger et al.: Journal of Polymer Science, vol. 62, No. 173 (1962),pp. 81$2, QD 281P6I62.

WILLIAM H. SHORT, Primary Examiner. L. M. PHYNES, Assistant Examiner.

